The present invention relates to processes and apparatus for identifying the characters which are formed on a plurality of sheets of silicon, whereby the sheets are arranged in parallel planes and are aligned relative to the means of support, and comprises at least illuminating the characters on a sheet, observing the illuminated characters and identifying the characters which have been observed.
The prior art teaches such a process and device, particularly by means of the document WO 91/10968. More especially, this document describes, in particular, an apparatus for identifying marks which are engraved on sheets of silicon which are aligned in a slide magazine, i.e.! an apparatus in which a luminous ray is reflected by one or two mirrors before illuminating the marks, which are located on the sheet and which are to be identified, whereby the image of the marks, which have been illuminated in this way, is reflected by two mirrors before entering, the observation camera. In order to illuminate the marks, which are engraved on the sheets which are aligned in the slide magazine, the apparatus comprises means for raising the sheet, which is positioned directly in front of the sheet which is to be identified, in order to permit the placement of a mirror opposite the marks, the mirror being positioned at 45.degree. relative to the plane which is defined by the sheet.
This apparatus exhibits the disadvantage of necessitating the manipulation of a sheet in order to permit the identification of another sheet, whereby this can engender the risk of particulate contamination of the sheets and, in addition, the identification times are slowed down by these manipulations. Moreover, this apparatus uses several mirrors in order to observe the illuminated marks, whereby this therefore entails increased complexity of the mechanisms and an elevated cost price for the apparatus and can cause errors in the identification of sheets which are due to multiple reflections of the image by the mirrors prior to entering the observation camera.